1. Field of the Invention
This invention relates to optical systems, more specifically, a method to control operation of these systems, or devices within them.
2. Background of the Invention
To be able to control at what levels of light optical systems operate is desirable for many reasons. Two of these reasons are to prevent pirating of devices, and to save wear and tear on the system.
A manufacturer may produce an optical system that has three different markets, depending on the size of the system. For example, in displays, three possible markets could be commercial projection systems, large screen televisions (greater that thirty inches) and smaller screen televisions. The same devices, optical memories, spatial light modulators or other light sensitive devices could be used in each. Nothing would prevent a person from buying the smaller, less expensive television and pirating the parts to make a large screen television, or a projection system.
The common element in the systems is the use of light. But each level of system, in either size or complexity, requires a different level of light. The large projection system may require high levels of illumination and the television a much lower level. It would benefit the manufacturer to be able to limit the devices in each system to a certain window of illumination that the system can operate at.
Another important reason to control the operation would be to prevent damage to the parts of a system. If a system only works efficiently at a certain level of illumination, it only causes needless wear to operate the system at a level where it operates inefficiently. Further, individual devices may be damaged at very high levels of illumination. If there were a problem in the system, where too much light was impinging upon the device, the device should be able to be shut down to prevent damage.